The overall goal of this laboratory is to understand the regulation and physiological significance of brain-pituitary-adrenocortical function. The specific aims of this application are 4: 1) To determine whether specific inputs to ACTH secretion stimulated by hypoxia are mediated by noradrenergic pathways from the medulla to the paraventricular nuclei of the hypothalamus. These neurochemical studies will determine whether catecholaminergic inputs to PNV from the medulla are stimulated by hypoxia using electrical stimulation and pharmacological stimulation of medulla and pharmacological blockade of PVN to test the hypothesis. 2) To consolidate evidence for a reset of the controller for diurnal adrenocortical function, to delineate the requirements for the feedback sensor or comparator, and to delineate the brain site for diurnal reset in the adrenocortical system. 3) To determine the effects of glucocorticoid removal and replacement on the isolated pituitary and separately the pituitary-hypothalamus in vivo. 4) To determine the role of corticosteroids in the responses of rats to nutritional stress, and to compare the effects of diurnal elevations in corticosteroids with constant levels of glucocorticoids on food intake, insulin secretion and lipogenesis or fat accretion.